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I have searched a lot for a content addressable memory chip, but I couldn't find any part numbers. Why aren't there any chips for this kind of memory?!

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  • \$\begingroup\$ You're looking in the wrong databooks. Try some from the late 1980s or early 1990s. \$\endgroup\$ – Brian Drummond Apr 8 '18 at 12:00
  • \$\begingroup\$ @BrianDrummond - which sort-of implies that they were never really used for much ... \$\endgroup\$ – brhans Apr 8 '18 at 12:03
  • \$\begingroup\$ Definite niche. Can't find the AMD one, but found this engineeringspecifier.com/around-the-industry/… \$\endgroup\$ – Brian Drummond Apr 8 '18 at 12:06
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    \$\begingroup\$ Also found a Synchronous one, though it might be a SCAM. digchip.com/datasheets/parts/datasheet/326/NL82721.php \$\endgroup\$ – Brian Drummond Apr 8 '18 at 12:10
  • \$\begingroup\$ @BrianDrummond I am looking in Mouser and Digikey. There is only one CAM in the memory section of Digikey. Also, no distributor has NL82721! \$\endgroup\$ – M.H Apr 8 '18 at 12:21
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Because there never was an application that required enough chips in a fixed configuration to justify producing a standard chip.

Generally speaking, each application requires a unique configuration, and it usually makes more sense to integrate the CAM with other application-specific logic in an ASIC.

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  • \$\begingroup\$ Or with an FPGA too. \$\endgroup\$ – Michael Karas Apr 8 '18 at 12:22
  • \$\begingroup\$ What do you mean by the configuration? What specific configuration does a CAM have except its data width and depth? \$\endgroup\$ – M.H Apr 8 '18 at 12:23
  • \$\begingroup\$ FPGA. About that... I found a Xilinx datasheet (DS253, PDF) dated 2008. And marked "Discontinued IP". :-( In a locked filing cabinet, in a disused broom cupboard at the bottom of the stairs. \$\endgroup\$ – Brian Drummond Apr 8 '18 at 12:30
  • \$\begingroup\$ I seem to recall Signetics having one in their databook at one time. An idea from the past that never seemed to be viable in the market. \$\endgroup\$ – AlmostDone Apr 8 '18 at 12:39
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    \$\begingroup\$ CAMs are still in wide use, actually - but they are built into specialised ASICs instead of being available as discrete components. For example, the tag memory of a set-associative cache is a small (and very fast) CAM. \$\endgroup\$ – Chromatix Apr 8 '18 at 12:46

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